LONDON, England (CNN) -- Queen Elizabeth helped launch Heathrow's $8.6 billion new Terminal 5 on Friday as part of the British airport's rejuvenation plan to maintain its status as one of the world's most important transport hubs.

A general view of the new Terminal 5 at Heathrow Airport prior to its official opening on Friday.

The British monarch, who also opened Heathrow's first passenger terminal in 1955, was present under strict security a day after a man carrying a backpack was arrested for running onto a runway at the airport.

The first flights from the new terminal are scheduled for March 27.

Its opening has come after 15 years of planning and construction by its owners BAA -- and protests by local residents and environmental groups.

It is part of a strategy which could lead to passenger numbers almost doubling to 122 million a year, with a sixth terminal and a third runway in the pipeline despite some vociferous opposition.

Spanish-owned BAA, which also runs Gatwick and Stansted in Britain, also plans to eventually demolish Terminals 1 and 2 and replace them in a project called Heathrow East. Watch Queen Elizabeth meet airport staff. »

Residents were once told by BAA that there would be no fifth terminal, but the company is planning to forge further ahead despite the concerns of environmental groups.

"Domestic air links to Heathrow are particularly valuable for the regional economies, and this new terminal will undoubtedly provide them with a much-needed boost. The passage of the current Planning Bill must ensure that this is the last airport which has to endure such an absurdly protracted planning process." See British Airways chief executive Willie Walsh's views on the terminal. »

Visit London chief executive James Bidwell said: "T5 will provide visitors to London and the UK with a spectacular first impression and alleviate the pressure experienced at Heathrow, the world's busiest airport.

"The terminal's smoother check-in process and state-of-the-art baggage management system will certainly better the tourist experience and should help improve the airport's international reputation." E-mail to a friend